The present invention relates to a metallic wire for cutting, grinding or chamfering processing of hard materials and the like and, in particular, to a metallic wire for cutting and grinding processing having abrasive grain powder arranged and retained uniformly and firmly in the surface layer and to a method for producing the metallic wire.
In recent years, the use of a metallic wire for the cutting of hard materials such as ceramics and the like or semiconductor materials such as silicon, gallium arsenic, and the like and further for chamfering processing of fine through holes in workpieces has been studied and carried out.
As a wire used for the above-mentioned uses, a wire with high tensile strength, that is, a so-called saw wire is used. In this case, processing such as cutting or the like is carried out under the condition in which free abrasive grains are existing between the wire and a material to be processed and grinding actions are performed only by frictional force, so that a problem bad efficiency is presented.
Further, for the cutting, there is a so-called electro-spark machining method in which a high voltage is applied between the wire and a material to be cut to cut the material by discharge between the both. The method, however, has a problem that the material to be cut is limited only to electroconductive materials.
Recently, a diamond wire produced by coating the surface of a wire with diamond powder by a plating process has been developed and an efficient processing method using the wire and utilizing the grinding force of the diamond powder on the surface of the wire has begun to be studied. However, the diamond powder is only stuck to the wire surface mainly by a Cu or Ni plating layer, so that it has weak adhesion to the surface and also the uniform arrangement and retention of it over the whole surface of the wire are difficult. Therefore, such a method may be reminded that diamond powder is mixed in usual bond metal powder such as Ni, Cu, or the like and then the mixed material is sintered and fixed to the whole surface of wire to produce a diamond wire by applying a usual manufacturing technology for a diamond grindstone.
However, even if the above-mentioned method of sintering and fixing the diamond powder mixed with the bond metal powder to the whole surface of the wire is an ideal method certainly, it is impossible by any means to produce such a long and thin wire by a usual sintering method at present.
On the other hand, double-structure wires such as wires coated with copper or aluminum are now in general use. If such an abrasive grain/steel structure wire as aimed by the invention is taken as a mere double-structure steel wire and a conventional manufacturing technology for the double-structure wires is applied to produce the abrasive grain/steel structure wire, a die for wire drawing is markedly attacked and abraded by the abrasive grains, for example, in a wire drawing process, so that it is impossible practically to apply the conventional wire drawing processing technology to the production of the above-mentioned abrasive grain/steel structure wire.